LA 3644 X-Plosives

最简单的并查集

多做做水题，加深一下理解

 //#define LOCAL
 #include <cstdio>
 
 const int maxn =  + ;
 int parent[maxn];
 
 int GetParent(int a) { return parent[a] == a ? a : parent[a] = GetParent(parent[a]); }
 
 int main(void)
 {
     #ifdef LOCAL
         freopen("3644in.txt", "r", stdin);
     #endif
 
     int x, y;
     while(scanf("%d", &x) == )
     {
         for(int i = ; i < maxn; ++i)    parent[i] = i;
         int cnt = ;
         while(~x)
         {
             scanf("%d", &y);
             x = GetParent(x); y = GetParent(y);
             if(x == y)    ++cnt;
             else        parent[x] = y;
             scanf("%d", &x);
         }
         printf("%d\n", cnt);
     }
     return ;
 }

代码君